Parking support method and parking support device

ABSTRACT

A parking assist method for assisting parking of a subject vehicle uses a parking assist apparatus comprising a controller and a display. The controller guides the subject vehicle to a parking space. The parking assist method includes detecting available parking spaces into which the subject vehicle can be parked, setting a parking space suitable for parking of the subject vehicle among the detected plurality of available parking spaces as a recommended available parking space in accordance with the traveling state of the subject vehicle, displaying the recommended available parking space on the display, setting the recommended available parking space displayed on the display as a target parking space for the subject vehicle on the basis of an operation by a driver or passenger, and performing automated control of the subject vehicle to park the subject vehicle into the target parking space.

TECHNICAL FIELD

The present invention relates to a parking assist method and a parkingassist apparatus.

BACKGROUND

Heretofore, a parking space recognition apparatus has been known asbelow. The parking space recognition apparatus detects spaces into whicha subject vehicle can spatially enter, prioritize the spaces on thebasis of preregistered unique information of the subject vehicle and/orthe driver, and outputs a candidate parking space (see Japanese PatentApplication JP2009-205191A).

However, when attribute information of the subject vehicle or the uniqueinformation of the driver is not registered, an appropriate parkingspace cannot be presented to the driver and passengers.

A problem to be solved by the present invention is to provide a parkingassist method or a parking assist apparatus with which an appropriateparking space can be presented to the driver and passengers.

SUMMARY

The present invention solves the above problem through setting a parkingspace suitable for parking of a subject vehicle among detected availableparking spaces as a recommended available parking space in accordancewith the traveling state of the subject vehicle, displaying therecommended available parking space on a display, setting therecommended available parking space displayed on the display as a targetparking space for the subject vehicle on the basis of an operation by adriver or passenger, and performing automated control of the subjectvehicle to park the subject vehicle into the target parking space.

The present invention has an effect that an appropriate availableparking space can be presented to the driver and passengers because therecommended available parking space suitable for parking is displayed onthe display while setting the recommended available parking space amongthe available parking spaces so that it matches estimation of thevehicle's behavior.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a parking assistsystem according to one or more embodiments of the present invention;

FIG. 2 is a flowchart illustrating an example of a control procedure inthe parking assist system according to one or more embodiments of thepresent invention;

FIG. 3 is a view illustrating an example of positions at which on-boardcameras are arranged according to one or more embodiments of the presentinvention;

FIG. 4A is a first view for describing an example of a parking assistprocess according to an embodiment of the present invention;

FIG. 4B is a second view for describing an example of the parking assistprocess according to the embodiment;

FIG. 4C is a third view for describing an example of the parking assistprocess according to the embodiment;

FIG. 4D is a fourth view for describing an example of the parking assistprocess according to the embodiment;

FIG. 4E is a view for describing an example of the parking assistprocess according to the embodiment;

FIG. 4F is a view for describing an example of the parking assistprocess according to the embodiment;

FIG. 5 is a graph illustrating the relationship between a vehicle speed(V [km]) and a gaze point distance (Y [m]);

FIGS. 6A-6C are a set of views illustrating examples of parking patternsto which the parking assist process according to the embodiment isapplied;

FIG. 7A is a first view for describing an example of a display screen inthe parking assist process according to the embodiment;

FIG. 7B is a second view for describing an example of a display screenin the parking assist process according to the embodiment;

FIG. 7C is a third view for describing an example of a display screen inthe parking assist process according to the embodiment;

FIG. 7D is a fourth view for describing an example of a display screenin the parking assist process according to the embodiment;

FIG. 7E is a view for describing an example of a display screen in theparking assist process according to the embodiment;

FIGS. 8A and 8B are a set of views for describing an example of aparking assist process according to another embodiment of the presentinvention; and

FIG. 9 is a graph illustrating the relationship between a vehicle speed(V [km]) and a gaze point distance (Y [m]).

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

First Embodiment

In this embodiment, the present invention will be described withreference to an example in which the parking assist apparatus accordingto the present invention is applied to a parking assist system equippedin a vehicle. The parking assist apparatus may also be applied to aportable terminal device (equipment such as smartphone and PDA) capableof exchanging information with onboard devices. The method of displayingparking assist information according to the present invention can beused in a parking assist apparatus. Parking assist information relatingto the invention of the displaying method is specifically displayedusing a display 21.

FIG. 1 is a block diagram of a parking assist system 1000 having aparking assist apparatus 100 according to one or more embodiments of thepresent invention. The parking assist system 1000 according to thepresent embodiment assists an operation of moving (parking) a subjectvehicle into a parking space. The parking assist system 1000 accordingto the present embodiment includes cameras 1 a to 1 d, an imageprocessing device 2, a ranging device 3, the parking assist apparatus100, a vehicle controller 30, a drive system 40, a steering angle sensor50, and a vehicle speed sensor 60. The parking assist apparatus 100according to the present embodiment includes a control device 10 and anoutput device 20. The output device includes a display 21, a speaker 22,and a lamp 23. These components are connected to one another via acontroller area network (CAN) or other in-vehicle LAN to mutuallyexchange information.

The control device 10 of the parking assist apparatus 100 according tothe present embodiment is a specific computer comprising a ROM 12 thatstores a parking assist program, a CPU as an operation circuit thatexecutes the program stored in the ROM 12 to serve as the parking assistapparatus 100 according to the present embodiment, and a RAM 13 thatserves as an accessible storage device.

The parking assist program according to the present embodiment is aprogram for execution of a control procedure of presenting parkingspaces, into which parking is possible, on the display 21 and assistingan operation to park the subject vehicle into a parking space set by auser. The parking assist apparatus 100 according to the presentembodiment can be applied to automated parking in which all of thesteering, accelerator, and brake are automatically operated thereby topark a vehicle automatically and can also be applied to semiautomatedparking in which at least one operation of the steering, accelerator,and brake is manually performed and other operations are automaticallyperformed for parking. In addition or alternatively, the parking assistapparatus 100 can be applied to a parking assist function with which aroute to a parking space is presented to the user and the user operatesthe steering, accelerator, and brake to park the vehicle.

The control device 10 of the parking assist apparatus 100 according tothe present embodiment has functions of executing an informationacquisition process, an available parking space detection process, arecommended available parking space detection process, and a displaycontrol process. Each of the above processes is executed by cooperationof software for implementing the process and the above-describedhardware.

FIG. 2 is a flowchart illustrating a control procedure of the parkingassist process executed by the parking assist system 1000 according tothe present embodiment. The trigger for starting the parking assistprocess is not particularly limited, and the parking assist process maybe triggered by the operation of a start switch of the parking assistapparatus 100.

The parking assist apparatus 100 according to the present embodiment hasa function for automatically moving the subject vehicle to the parkingspace. In this process according to the present embodiment, amomentary-type switch such as a deadman switch is used. In the parkingassist apparatus 100, the automated driving of the subject vehicle isexecuted when the deadman switch is pressed and the automated driving ofthe subject vehicle is suspended when the pressing of the deadman switchis released.

Specifically, in step 101, the control device 10 of the parking assistapparatus 100 according to the present embodiment acquires imagescaptured by the cameras 1 a to 1 d attached to multiple sites of thesubject vehicle. The cameras 1 a to 1 d capture images of boundary linesof parking spaces around the subject vehicle and objects existing aroundthe parking spaces. The cameras 1 a to 1 d may be CCD cameras, infraredcameras, or other appropriate imaging devices. The ranging device 3 maybe provided at the same position as any of the cameras 1 a to 1 d or mayalso be provided at a different position. The ranging device 3 may be aradar device, such as a millimeter-wave radar, laser radar andultrasonic radar, or a sonar. The ranging device 3 detects the presenceor absence of objects, positions of the objects, and distances to theobjects on the basis of the received signal of the radar device. Suchobjects correspond to obstacles, pedestrian, and other vehicles aroundthe vehicle. The received signal is used to determine whether or not theparking space is empty (whether or not a vehicle is parked in theparking space). Obstacles may be detected using the motion stereotechnique by the cameras 1 a to 1 d.

FIG. 3 is a view illustrating an exemplary arrangement of the cameras 1a to 1 d disposed on the subject vehicle. In the example illustrated inFIG. 3, the camera 1 a is disposed on the front grille part of thesubject vehicle, the camera 1 d is disposed in the vicinity of the rearbumper, and the cameras 1 b and 1 c are disposed on the lower parts ofthe right and left door mirrors. The cameras 1 a to 1 d may each be acamera having a wide-angle lens with a wide view angle.

In step 101, the control device 10 also acquires ranging signals fromthe ranging device 3, which may be a plurality of modules attached tomultiple sites of the subject vehicle.

In step 102, the control device 10 of the parking assist apparatus 100controls the image processing device 2 to generate an overhead image. Onthe basis of the acquired plurality of captured images, the imageprocessing device 2 generates an overhead image in which the surroundingstate including the subject vehicle and the parking space for thesubject vehicle to park is viewed from a virtual viewpoint P (see FIG.3) above the subject vehicle. The image processing performed by theimage processing device 2 may be conducted, for example, using a methodas disclosed in “Development of Around View System, Proceedings ofSociety of JSAE Annual Congress, 116-07 (October 2007), pp. 17-22,SUZUKI Masayasu, CHINOMI Satoshi, TAKANO Teruhisa.” Examples of agenerated overhead image 21A are illustrated in FIGS. 7A and 7B, whichwill be described later. These figures each illustrate a display examplethat simultaneously displays the overhead image (top view) 21A aroundthe subject vehicle and a monitoring image (normal view) 21B around thesubject vehicle.

In step 103, available parking spaces Me are detected. The controldevice 10 detects the available parking spaces Me on the basis of theimages captured by the cameras 1 a to 1 d and/or the data received bythe ranging device 3. The control device 10 stores a “parking possiblecondition” for extracting the available parking spaces Me. The “parkingpossible condition” is defined from the viewpoint of extracting aparking space into which parking is possible. The “parking possiblecondition” is preferably defined from the viewpoint of the distance fromthe subject vehicle, the viewpoint as to whether or not other vehiclesare parked, and the viewpoint of presence or absence of obstacles. Onthe basis of the “parking possible condition,” the control device 10detects the available parking spaces Me into which the subject vehiclecan be parked. The available parking spaces Me are parking spaces intowhich the subject vehicle can be parked. The control device 10 detectsthe available parking spaces Me on the basis of the images captured bythe cameras 1 a to 1 d and/or the data received by the ranging device 3.In the above description, images of available parking spaces arecaptured by the on-board cameras and the available parking spaces Me aredetected from the captured images, but information may be acquired froman external server and the available parking spaces may be specifiedfrom the acquired information.

A method of detecting the available parking spaces Me will be describedbelow. The control device 10 determines whether or not the subjectvehicle is traveling in an area that includes parking spaces (such anarea will also be referred to as a “parking area,” hereinafter), on thebasis of the vehicle speed or positional information from a navigationsystem (not illustrated). For example, when the vehicle speed of thesubject vehicle is a predetermined vehicle speed threshold or less andthis state continues for a predetermined time or more, the controldevice 10 determines that the subject vehicle is traveling in a parkingarea. In addition or alternatively, when the detected positionalinformation has an attribute that represents a parking area such as anarea including parking spaces of a highway, for example, the controldevice 10 determines that the subject vehicle is traveling in theparking area. In the present embodiment, a determination may be made asto whether or not the detected area is an area including availableparking spaces, via communication with the outside of the vehicle, thatis, via so-called road-to-vehicle communication or vehicle-to-vehiclecommunication.

When a determination is made that the subject vehicle is traveling in aparking area, the control device 10 detects white lines on the basis ofthe captured images acquired for generation of an overhead image. Whitelines represent boundary lines that define frames (regions) of parkingspaces. The control device 10 performs edge detection on the capturedimages to calculate a luminance difference (contrast). The controldevice 10 specifies a pixel line having a luminance difference of apredetermined value or more from the overhead image and calculates thewidth and length of the line. The control device 10 also detects whetheror not there are candidates of parking frame lines that have a higherpossibility of being lines of parking frames than the specified line,around the portion in which the line is specified. For example, when aline having a larger luminance difference is newly specified, the newlyspecified line is detected as a line having a higher possibility ofrepresenting a parking frame line. In the present embodiment, framelines representing parking spaces are not necessarily white, and othercolors such as red may also be employed.

The ROM 12 of the control device 10 preliminarily stores information onthe patterns of parking frames. The patterns of parking frames representvarious shapes of parking spaces. For example, in the parking spaces ofFIG. 6A which will be described later, the pattern of a parking frame iscomposed of three sides among the sides which form a rectangle. Examplesof parking frame patterns include those for parallel parking asillustrated in FIG. 6B, which will be described later, and those foroblique-parking as illustrated in FIG. 6C, which will also be describedlater.

The control device 10 specifies lines located on the road surface fromthe overview image as candidates of parking frame lines using a knownimage processing technique such as pattern matching. When the specifiedcandidates of parking frame lines satisfy all of the following threeconditions (1) to (3), the control device 10 specifies the specifiedparking frame lines as those representing parking spaces. The followingconditions are merely examples.

(1) Lines extracted as candidates of parking frame lines do not includea line having a length equal to or larger than a first line lengththreshold that is preliminarily set (e.g. a length corresponding to anactual distance of 15 [m]).

(2) Among lines extracted as candidates of parking frame lines, a set ofadjacent two lines within a first line spacing range that ispreliminarily set (e.g. a length corresponding to an actual distance of3 to 5 [m]) does not include a set of lines having a length equal to orsmaller than a second line length threshold that is preliminarily set(e.g. a length corresponding to an actual distance of 7 [m]).

(3) Among lines extracted as candidates of parking frame lines, a set ofadjacent two lines within a second line spacing range that ispreliminarily set (e.g. a length corresponding to an actual distance of2.5 to 5 [m]) does not include a set of lines having a length equal toor smaller than a third line length threshold that is preliminarily set(e.g. a length corresponding to an actual distance of 15 [m]).

In case of specifying parking spaces that satisfy the above threeconditions, the control device 10 determines whether or not obstaclesare present in the specified parking spaces using the detection datafrom the ranging device 3. In addition, the control device 10 determineswhether or not the specified parking spaces are those into which parkingis possible by automated driving, on the basis of a travel route in theautomated driving. For example, parking spaces for which a travel routein the automated driving cannot be ensured, such as parking spacesfacing a wall, do not correspond to parking spaces into which parking ispossible by the automated driving. Then, the control device 10 detectsparking spaces, from among the specified parking spaces, in whichobstacles do not exist and into which parking is possible by theautomated driving, as the available parking spaces Me. Thus, the controldevice 10 detects the available parking spaces Me. In the abovedescription, the control device 10 detects the available parking spaceswhile detecting parking frame lines, but the parking frame lines may notnecessarily be detected to detect the available parking spaces. Inaddition or alternatively, the control device 10 may detect empty spaceshaving a certain range and detect the empty spaces as the availableparking spaces and may also detect the available parking spaces usinginformation about past results of parking. In addition or alternatively,when parking spaces satisfy a predetermined condition, the controldevice 10 may detect the parking spaces satisfying the predeterminedcondition as the available parking spaces.

FIG. 4A is a first view for describing an example of the parking assistprocess according to the present embodiment. It is assumed that, in FIG.4A, the position of the subject vehicle traveling is P1 and the vehiclespeed is V1. Arrows L represent a travel route when the vehicle isparked by automated driving. Dotted circles represent the availableparking spaces Me detected at the position P1.

In FIG. 4A and in FIGS. 4B to 4D which will be described later, themovement of the subject vehicle is represented in a temporal sequence,and the position of the subject vehicle moves from FIG. 4A in the orderof FIG. 4B, FIG. 4C, and FIG. 4D. FIG. 4E, which will be describedlater, is not continuous with FIGS. 4A to 4D in the temporal sequence.

The travel route L is a route on which the subject vehicle moves fromthe current position G1 to an intermediate position Mw located ahead ofthe subject vehicle and reverses to complete the parking maneuver intoan available parking space PL. Such parking maneuver includes one ormore turns for parking. In FIG. 4A, an obstacle M1 exists on the parkingspace PR8, and the control device 10 therefore does not detect theparking space PR8 as an available parking space Me. With regard to theparking space PL8, a travel route cannot be ensured in the automateddriving because a wall Wa interferes with the travel route(corresponding to dotted arrows in FIG. 4A), and the parking space PL8is therefore not a parking space suitable for the automated driving.Accordingly, the control device 10 does not detect the parking space PR8 as an available parking space Me. Other vehicles are parked in theparking spaces PR1, PR4, PR6, and PL3, and the control device 10therefore does not detect them as available parking spaces Me. Thecontrol device 10 detects the parking spaces PL1, PL2, PL4 to PL7, PR2,PR3, PR5, and PR7 as available parking spaces Me.

The control apparatus 10 sets a range that includes the parking spacesPL2 to PL5 and PR2 to PR5, among the parking spaces included in theimages captured at the position P1 of the subject vehicle, as thedetection range for available parking spaces Me. The detection range foravailable parking spaces Me during the vehicle's travel is not limitedto the range of parking spaces PL2 to PL5 and PR2 to PR5, and may alsobe the range of parking spaces PL1 to PL8 and PR1 to PR8, for example.

Referring again to FIG. 2, in step 104, a recommended available parkingspace Mr is detected. The recommended available parking space Mr is anavailable parking space suitable for parking the subject vehicle. Thecontrol device 10 detects the recommended available parking space Mr inaccordance with the traveling state of the subject vehicle from amongthe detected plurality of available parking spaces. The control device10 stores the “parking recommendation condition” for extracting therecommended available parking space Mr. The “parking recommendationcondition” is defined from the viewpoint of extracting a parking spacewith which a parking-related cost required for parking is low. The“parking recommendation condition” is preferably defined from theviewpoint of a time required for parking (required time for parking). Onthe basis of the “parking recommendation condition,” the control device10 extracts the recommended available parking space Mr, with which theparking-related cost is low, from among the available parking spaces.

A method of detecting the recommended available parking space Mr will bedescribed below. The control device 10 evaluates the parking-relatedcost required for parking into each available parking space. The travelroute used for evaluation of the cost is a route from the start positionat which the parking assist process (automated driving) is started tothe position of each available parking space Me. The control device 10calculates the travel route when parking the subject vehicle into eachavailable parking space Me. The control device 10 sets the startposition for each available parking space Me. The control device 10calculates a travel route from the start position to each availableparking space Me. The number of travel routes for the automated drivingis not limited to one, and the control device 10 may calculate aplurality of travel routes in accordance with the surroundingsituations.

The parking-related cost for parking into each available parking spaceMe reflects a load such as the required time for parking which isrequired for moving the subject vehicle to the parking space by theautomated driving.

The parking-related cost reflects a travel time for the subject vehicleto be parked into an available parking space Me by the automated drivingand is obtained in accordance with the required time for parking. Therequired time for parking is a time when traveling by the automateddriving along the travel route calculated for each available parkingspace Me. The parking-related cost may be obtained in accordance withthe ease of entry into an available parking space Me. The ease of entryinto an available parking space Me is determined in accordance with thetravel distance, the number of operations (the number of turns forparking), the maximum steering angle, the vehicle speed, etc. Forexample, when the travel distance is long, when the number of turns forparking is large, when the maximum steering angle is large, and/or whenthe vehicle speed is high, it is not easy to enter an available parkingspace Me, and the parking-related cost is high. In other words, the easeof entry is evaluated for each available parking space, and on theassumption that an available parking space into which entry is easiestis the available parking space with which the parking-related cost issmallest, the available parking space may be set as the recommendedavailable parking space. Factors of the parking-related cost may includenot only the required time for parking but also other factors such asthe certainty of parking in the automated driving. The parking-relatedcost may not necessarily be an index equivalent to the required time forparking and may also be calculated from the relative relationship withthe number of turns for parking on a travel route, the length of atravel route, or the maximum steering angle. The parking-related costmay be calculated on the basis of each index, such as the required timefor parking, the ease of entry into an available parking space Me, andthe certainty of parking, or on the basis of a combination of two ormore indices, or on the basis of a combination of all the indices.

In the following description of the present embodiment, theparking-related cost is calculated on the basis of the required time forparking. The travel route is different for each available parking spaceMe in accordance with the number of turns for parking, the traveldistance, the maximum steering angle, etc. When the vehicle travelsalong a travel route by the automated driving, therefore, the requiredtime for parking is different for each travel route. For example, therequired time for parking will be shorter as the number of turns forparking is smaller, as the distance of a travel route is shorter, or asthe maximum steering angle is smaller. As illustrated in FIG. 4A, on theassumption of parking into the available parking space PL6 or PL7, thedistance from the vicinity of the parking space PL7 to the wall Wa isshorter than the distance from the vicinity of the parking space PL6 tothe wall Wa. The number of turns for parking when parking into theparking space PL7 is therefore larger than the number of turns forparking when parking into the parking space PL6, and the required timefor parking into the parking space PL7 is longer than the required timefor parking into the parking space PL6 (the parking-related cost ishigher in the former case).

The control device 10 then calculates a gaze point distance on the basisof the vehicle speed of the subject vehicle. The gaze point distancerefers to a distance from the position of the subject vehicle to theposition which the driver of the subject vehicle gazes on. In general,the higher the vehicle speed, the farther the driver gazes on, and thelower the vehicle speed, the closer the driver gazes on. From theviewpoint of recommending an available parking space in accordance withthe observing point of the driver, the control device 10 sets a longergaze point distance as the vehicle speed of the subject vehicle ishigher, and sets a shorter gaze point distance as the vehicle speed ofthe subject vehicle is lower. This allows the parking assist into theavailable parking space to be executed in accordance with the intentionof the driver. The gaze point distance does not have to be linear andmay also be defined along a curve. When the gaze point distance isdefined along a curve, the curvature of the curve may be associated withthe steering angle.

FIG. 5 is a graph illustrating the relationship between the vehiclespeed (V [km/s]) and the gaze point distance (Y [m]). The solid linerepresents a characteristic when the vehicle speed increases while thebroken line represents a characteristic when the vehicle speeddecreases. As illustrated in FIG. 5, when the vehicle speed is Va orlower, the gaze point distance is Ya. When the vehicle speed increasesfrom Va to Vc, the gaze point distance maintains Ya. Then, as thevehicle speed increases from the state of Vc, the gaze point distanceincreases in proportion to the vehicle speed within a range of Vc orhigher and Vd or lower of the vehicle speed. When the vehicle speed isVd or higher, the gaze point distance maintains Yb. On the other hand,when the vehicle speed lowers from the state of Vd, the gaze pointdistance maintains Yb until the vehicle speed returns to Vb from Vd. Thegaze point distance decreases in proportion to the vehicle speed withina range of Va or higher and Vc or lower of the vehicle speed. Thus, therelationship between the vehicle speed and the gaze point distance has ahysteresis characteristic between the increasing direction anddecreasing direction of the vehicle speed.

The ROM 12 of the control device 10 stores the relationship between thevehicle speed and the gaze point distance as a map. When acquiring theinformation on the vehicle speed from the vehicle speed sensor 60, thecontrol device 10 refers to the map to calculate the gaze point distancecorresponding to the vehicle speed.

FIG. 4B illustrates a state in which the subject vehicle moves forwardfrom the position P1 illustrated in FIG. 4A to a position P2. The speedof the subject vehicle at the position P2 is V2 (<V1). The controldevice 10 refers to the map to calculate the gaze point distancecorresponding to the vehicle speed V2. The control device 10 specifies apoint G2 that is separate from the position P2 by the gaze pointdistance, as a gaze point (G2). The subject vehicle is in a state ofselecting an available parking space with the lowered vehicle speed V2(<V1). The distance between the gaze point G2 and the subject vehicle isshorter than the distance between the gaze point G1 illustrated in FIG.4A and the subject vehicle because the vehicle speed is lowered.

In the state illustrated in FIG. 4B, the control device 10 detects arecommended available parking space from among the available parkingspaces PL2, PL4, PL5, PR2, PR3, and PR5 in the vicinity of the gazepoint G2. The control device 10 detects the recommended availableparking space on the basis of the parking-related cost for each of theparking spaces PL2, PL4, PL5, PR2, PR3, and PR5.

The control device 10 then assigns numbers for identification to theavailable parking spaces Me in the vicinity of the gaze point G2. Forexample, the identification numbers are given in the order of proximityto the gaze point G2. The control device 10 calculates theparking-related cost for parking into each available parking space Me(the parking-related cost represents an index of the ease of entry intoeach available parking space Me). The control device 10 may read out theparking-related cost for parking which is previously calculated.

To evaluate the parking-related cost, the control device 10 calculatesthe required time for parking into each available parking space Me. Inthe example of FIG. 4B, the control device 10 calculates theparking-related cost (required time for parking) for each of theavailable parking spaces PL2, PL4, PL5, PR2, PR3, and PR5 and stores theparking-related cost such that it is associated with each identificationnumber.

The control device 10 compares the required time for parking into eachavailable parking space Me with a predetermined required time threshold.The required time threshold is a value that is preliminarily set and anupper limit of the required time when parking by the automated driving.When the required time for parking into an available parking space Me islonger than the required time threshold, the control device 10 does notdetect the available parking space Me as the recommended availableparking space Mr.

After detecting the available parking spaces Me with which the requiredtime for parking is shorter than the required time threshold, thecontrol device 10 sets an available parking space Me that is closest tothe gaze point among the detected available parking spaces Me as therecommended available parking space Mr. In the example of FIG. 4B, therequired time for parking into the parking space PL4 is shorter than therequired time threshold, and the parking space PL4 is located closest tothe gaze point. The control device 10 therefore sets the parking spacePL4 as the recommended available parking space Mr. In theabove-described embodiment, among the available parking spaces Me withwhich the required time for parking is shorter than the required timethreshold, the available parking space with the shortest gaze pointdistance is set as the recommended available parking space Mr, butanother method may be employed to set the recommended available parkingspace Mr. For example, among the available parking spaces Me with whichthe required time for parking is shorter than the required timethreshold, an available parking space Me with which the required timefor parking is shortest may be set as the recommended available parkingspace Mr. In another embodiment, for example, it is assumed that, in thedetection of the recommended available parking space Mr, availableparking spaces Me can be set as the recommended available parking spaceMr when the gaze point distance from the gaze point to the availableparking space Me is within a predetermined distance. From among suchavailable parking spaces Me, an available parking space with which therequired time for parking is shortest may be detected as the recommendedavailable parking space Mr.

As described above, in the present embodiment, the gaze point distanceis calculated on the basis of the vehicle speed, and a position separatefrom the current position of the subject vehicle by the gaze pointdistance is specified as the gaze point. Further, among the availableparking spaces, an available parking space closest to the gaze point isset as the recommended available parking space Mr. That is, the gazepoint distance based on the vehicle speed is calculated to specify thegaze point of the user, thereby specifying the recommended availableparking space with consideration for the intention of the user (drivingoperation by the user). In the present embodiment, the parking-relatedcost is calculated for each available parking space, and among theavailable parking spaces, an available parking space with which theparking-related cost is low is set as the recommended available parkingspace Mr. That is, cost evaluation is employed to determine the state ofthe vehicle in the automated driving before the automated driving isexecuted, and the recommended available parking space is specified.Through this operation, in the present embodiment, an available parkingspace suitable for parking the subject vehicle is set as the recommendedavailable parking space in accordance with the traveling state of thesubject vehicle.

The control device 10 executes the detection process for the recommendedavailable parking space Mr at a predetermined period. As illustrated inFIG. 4C, also when the subject vehicle moves forward to the position P3at a vehicle speed of V3, the control device 10 detects a newrecommended available parking space Mr. The control device 10 calculatesa new gaze point G3 and the parking-related cost required for movingfrom the current position to each available parking space Me and detectsthe parking space PL5, with which the parking-related cost is lowest, asthe recommended available parking space Mr.

In step 105, the available parking spaces Me and the recommendedavailable parking space Mr are presented. The control device 10 controlsthe display 21 to display the set available parking spaces Me and theset recommended available parking space Mr thereby to present them tothe driver and passengers. The display form on the display 21 will bedescribed later.

In step 106, a determination is made as to whether or not a targetparking space Mo is input. The target parking space Mo is a parkingspace into which the vehicle is parked by the automated driving, andrepresents a location to be the target in the automated driving. Thetarget parking space Mo is set on the basis of the operation by thedriver or a passenger. For example, when the display 21 is a touchpanel-type display, the driver or a passenger touches a portionrepresenting a desired parking space thereby to designate the targetparking space Mo, and information on the target parking space Mo isinput to the control device 10.

When the target parking space Mo is input, the control flow proceeds tostep 107. On the other hand, when the target parking space Mo is notinput, the control flow returns to step 104, and the control flow fromstep 104 to step 106 is repeatedly executed.

When the target parking space Mo is input, this parking space is set asthe target parking space Mo in step S107.

In step 108, the control device 10 calculates a travel route for movingthe subject vehicle to the target parking space Mo.

FIG. 4D is a view illustrating a scene in which the available parkingspace PL5 is designated as the target parking space Mo. The controldevice 10 calculates a travel route for parking on the basis of thepositional relationship between the position P4 of the subject vehicleat which the parking maneuver (movement) is started (automated parkingstart position) and the position of the target parking space Mo.Although not particularly limited, the control device 10 calculates thetravel route to include two curves. The first curve lies from the stopposition of the subject vehicle, that is, the start position (P4) atwhich the parking assist is started, to the turning position Mw at whichthe turn for parking is performed. The second curve lies from theturning position Mw to the target parking space Mo (PL5).

The control device 10 reads travel routes corresponding to the selectedparking mode and calculates a travel route on the basis of thepositional relationship between the position of the subject vehicle whenstarting the automated parking process and the position of the targetparking space Mo. When the user presses the previously-described deadmanswitch during the operation of the automated parking mode, the controldevice 10 controls the vehicle controller 30 to execute the process ofmoving the subject vehicle to the target parking space Mo on thecalculated travel route.

The control device 10 calculates the travel route corresponding to eachof right-angle parking, parallel parking, and oblique parkingillustrated in FIGS. 6A-6C, respectively. In the present embodiment, thetravel route has been described as being calculated, but the presentinvention is not limited to this. In an alternative embodiment, a travelroute corresponding to the type of the parking space is stored in amemory (ROM), and the travel route may be read out when parking. Theparking mode (such as right-angle parking, parallel parking, and obliqueparking) may be selected by the driver of the subject vehicle.

In step 109, the parking assist apparatus 100 according to the presentembodiment executes the parking assist process or the automated parkingprocess. The parking assist apparatus 100 according to the presentembodiment controls the operation of the drive system 40 via the vehiclecontroller 30 so that the subject vehicle moves along the travel route.

The parking assist apparatus 100 according to the present embodimentincludes a parking assist control unit. The parking assist control unitacquires shift range information from an AT/CVT control unit, wheelspeed information from an ABS control unit, steering angle informationfrom a steering angle control unit, engine speed information from anECM, and other necessary information. On the basis thereof, the parkingassist control unit calculates and outputs instruction information onthe automated steering to the EPS control unit, instruction informationsuch as warning to a meter control unit, etc. The control device 10acquires information items, which are acquired by the steering anglesensor 50 of the steering apparatus of the vehicle and the vehicle speedsensor 60 and other sensors of the vehicle, via the vehicle controller30.

The drive system 40 according to the present embodiment allows thesubject vehicle to be parked into the target parking space Mo by drivingbased on the control command signals acquired from the parking assistapparatus 100. The steering apparatus according to the presentembodiment is a drive mechanism that moves the subject vehicle in theright and left directions. The EPS motor included in the drive system 40drives the power steering mechanism of the steering of the steeringapparatus on the basis of the control command signals acquired from theparking assist apparatus 100 to control the steering amount and assiststhe operation when moving the subject vehicle to the target parkingspace Mo. The content of the parking assist and the scheme of operationare not particularly limited, and schemes known at the time of filing ofthis application can be appropriately applied.

When the parking assist apparatus 100 according to the presentembodiment controls the subject vehicle to move to the target parkingspace Mo along the travel route calculated based on the position P4 ofthe subject vehicle and the position of the target parking space Mo, theoperation of the accelerator/brake is automatically controlled on thebasis of the designated control vehicle speed (set vehicle speed), andthe operation of the steering apparatus is also automatically controlledin accordance with the vehicle speed. The parking assist apparatus 100calculates command signals to the drive system 40 of the subjectvehicle, such as an EPS motor, while feeding back the output value ofthe steering angle sensor 50 of the steering apparatus so that thetravel trajectory of the subject vehicle coincides with the calculatedtravel route, and sends the command signals to the drive system 40 or tothe vehicle controller 30 which controls the drive system 40. That is,during the parking assist according to the present embodiment, thesteering operation and the accelerator/brake operation are automaticallyperformed. It is also possible to perform a parking process by remotecontrol that includes transmitting a setting command for the targetparking space Mo, a parking process start command, a parking suspensioncommand, etc. to the vehicle with no driver therein from the outside andperforming the parking.

As will be understood, it is also possible for the driver to operate theaccelerator/brake, and only the operation of the steering apparatus isautomated. In this case, the parking assist apparatus 100 controls thedrive system 40 on the basis of the set vehicle speed which ispreliminarily calculated so that the subject vehicle follows the travelroute to move, and controls the steering apparatus of the vehicle on thebasis of the set steering angle which is also preliminarily calculated.

A method of presenting parking assist information in the parking assistapparatus 100 according to the present embodiment will be describedbelow.

FIG. 7A is a first view for describing an example of a display screen inthe parking assist process according to the present embodiment. FIG. 7Bis a second view for describing an example of a display screen in theparking assist process according to the present embodiment. FIG. 7Aillustrates a display screen when the subject vehicle is traveling atthe position P2 of FIG. 4B. FIG. 7B illustrates a display screen whenthe subject vehicle is traveling at the position P3 of FIG. 4C. FIGS. 7Aand 7B represent the parking assist information displayed when searchingfor a parking space into which the subject vehicle is parked. What areillustrated in FIGS. 7A and 7B are situations in which the subjectvehicle searches for a parking space into which the subject vehicle isparked, while moving along the arrows.

In the display screen of FIG. 7A, an image (of boundary lines of parkingspaces) that indicates the parking spaces PL2 to PL5 and PR2 to PR5 isdisplayed on the left-side overhead image (top view) 21A on the screenof the display 21. In the display screen of FIG. 7B, an image (ofboundary lines of parking spaces) that indicates the parking spaces PL3to PL6 and PR3 to PR6 is displayed on the left-side overhead image (topview) 21A on the screen of the display 21. The center of the overheadimage (top view) 21A is displayed with an icon of the subject vehicleindicating the position of the subject vehicle. The monitoring image(normal view) can be displayed as any of images captured by differentcameras 1 a to 1 d in accordance with the operation state of the subjectvehicle. Examples illustrated in FIGS. 7A and 7B are each displayed asan image captured by the camera 1 a which is disposed on the front grillpart of the subject vehicle. When the subject vehicle moves back, themonitoring image may be displayed as an image captured by the camera 1 dwhich is disposed in the vicinity of the rear bumper. The image 21C isan image for messages. In these examples, the overhead image 21A and themonitoring image 21B are simultaneously displayed on the display 21, butonly the overhead image 21A may be displayed on the display 21, or onlythe monitoring image 21B may be displayed on the display 21.

The overhead image 21A is displayed with the available parking spaces Meand the recommended available parking space Mr. In a scene in which thesubject vehicle searches for a target parking space while moving in theparking lot, the available parking spaces Me and the recommendedavailable parking space Mr change as the subject vehicle moves. Theparking assist apparatus 100 displays the available parking spaces Meand the recommended available parking space Mr which are sequentiallydetected. The parking assist apparatus 100 displays the availableparking spaces Me with parking available marks in a circular shape anddisplays the recommended available parking space Mr with arecommendation mark in a rectangular shape.

As illustrated in FIGS. 7A and 7B, when the subject vehicle is moving,the available parking spaces Me and the recommended available parkingspace Mr sequentially change as the subject vehicle moves. When anavailable parking space Me or recommended available parking space Mrchanges, the parking assist apparatus 100 changes the position of theparking available mark or recommendation mark and displays it.

Here, a display form of the recommended available parking space Mr whenthe subject vehicle moves while decelerating will be described. Asdescribed above, the control device 10 sets the recommended availableparking space Mr for the available parking space Me which is closest tothe gaze point. The gaze point distance varies in accordance with thevehicle speed of the subject vehicle.

The description will be made for a case in which the characteristic ofthe gaze point distance when the vehicle speed increases and thecharacteristic of the gaze point distance when the vehicle speeddecreases follow the characteristic illustrated by the solid line ofFIG. 5 rather than the hysteresis characteristic as illustrated in FIG.5. It is assumed that, in the example of FIG. 4B, the recommendedavailable parking space Mr set when the vehicle speed is Vd is theavailable parking space PL5. In such a case, as the vehicle speedbecomes lower than Vd from the state of Vd, the gaze point distancebecomes shorter than Yb, and the recommended available parking space Mrchanges from the available parking space PL5 to another availableparking space PL4. That is, despite the fact that the subject vehicletravels toward the recommended available parking space Mr (PL5) which isset before deceleration, the screen of the display 21 shows a movementsuch that the frame of the recommended available parking space Mrreturns below on the screen (in the direction opposite to the traveldirection of the subject vehicle, i.e. in the negative direction of they-axis of FIG. 7A). To prevent such unnatural movement of therecommended available parking space Mr, in the present embodiment,hysteresis is given to the characteristic of the gaze point distancewith respect to the vehicle speed.

With the hysteresis characteristic, the gaze point distance ismaintained at Yb when the vehicle speed becomes lower than Vd from thestate of Vd. The recommended available parking space Mr thereforeremains at the position of the available parking space PL5 or moves tothe available parking space PL6 on the travel direction side of thevehicle from the position of the available parking space PL5. That is,among a first available parking space (corresponding to the availableparking space PL5 of FIG. 4A) and a second available parking space(corresponding to the available parking space PL4 of FIG. 4A) that aredisposed side by side along a direction parallel to the travel directionof the subject vehicle (the y-axis direction of FIG. 7A), the firstavailable parking space farther from the subject vehicle than the secondavailable parking space is set as the recommended available parkingspace by the control device 10. Then, in the state in which the vehiclespeed of the subject vehicle decreases, the control device 10 prohibitsthe recommended available parking space (corresponding to the availableparking space PL5 of FIG. 4A) from moving from the first availableparking space to the second available parking space (corresponding tothe available parking space PL4 of FIG. 4A) on the display screen of thedisplay 21. This can prevent the unnatural movement of the recommendedavailable parking space Mr.

Next, in a display form of the recommended available parking space Mr,hunting in the lateral direction (the positive and negative directionsof the x-axis of FIG. 7A) and control for preventing such hunting willbe described.

FIGS. 4E and 4F are views for describing an example of the parkingassist process according to the present embodiment. As described above,the recommended available parking space Mr changes its position on thedisplay screen of the display 21 in accordance with the position of thevehicle. For example, in the parking area illustrated in FIG. 4E, it isassumed that the subject vehicle is traveling between a row of parkingspaces on the left side and a row of parking spaces on the right side(the vicinity of the center in the lateral direction is indicated by adashed-two dotted line). It is also assumed that, as illustrated in FIG.4E, a number of parking spaces are empty in the parking area. When thesubject vehicle is traveling on the left side of the center lineindicated by the dashed-two dotted line, the position of the gaze pointis located on the left side of the center line. On the other hand, whenthe subject vehicle is traveling on the right side of the center lineindicated by the dashed-two dotted line, the position of the gaze pointis located on the right side of the center line. Accordingly, when thesubject vehicle travels in the vicinity of the center in the lateraldirection with respect to the direction in which the parking spaces arearranged, the position of the subject vehicle may swing laterally acrossthe center line, and the position of the gaze point will also swinglaterally. If the available parking space Me closest to the gaze pointis set as the recommended available parking space Mr, the displayedframe of the recommended available parking space Mr will frequently moveright and left. In the present embodiment, control is executed as belowto prevent such hunting of the recommended available parking space Mr.

The control device 10 sets a fixed display mode for fixing the displayregion for the recommended available parking space Mr in accordance withthe number of the available parking spaces Me. In the fixed displaymode, the region in which the recommended available parking space Mr canbe set is fixed to any of the left side and the right side. The controldevice 10 compares the number of the available parking spaces Me with apredetermined value. When the number of the available parking spaces Meis not smaller than the predetermined value, the control device 10 setsthe display mode to the fixed display mode.

When the fixed display mode is set, the control device 10 selects one ofright and left regions as a settable region for the recommendedavailable parking space Mr in accordance with the traveling state of thesubject vehicle. When the settable region is set, the control device 10sets the recommended available parking space among the available parkingspaces included in the settable region. The control device 10 calculatesthe distances from the parking spaces located on the sides of thesubject vehicle to the subject vehicle as lateral distances (XL, XR). Inthe examples of FIGS. 4E and 4F, XL represents the lateral distance onthe left side and XR represents the lateral distance on the right side.The control device 10 compares XL with XR. When XL is shorter than XR,the control device 10 sets the region on the left side as the settableregion for the recommended available parking space Mr. When XR isshorter than XL, the control device 10 sets the region on the right sideas the settable region for the recommended available parking space Mr.

After setting the settable region for the recommended available parkingspace Mr to the right or left, the control device 10 adds a length XHISto a length (W/2). The length (W/2) is a length obtained by halving thelength of the lateral distance between the left-side parking spaces andthe right-side parking spaces. The length XHIS is a length that definesa bias. When the left-side region is set as the settable region for therecommended available parking space Mr, the control device 10 comparesthe left-side lateral distance XL with a length (XHIS+W/2) to which thebias XHIS is added. When the left-side lateral distance XL is longerthan the length (XHIS+W/2), the control device 10 changes the settableregion for the recommended available parking space Mr from the left-sideregion to the right-side region. When the left-side lateral distance XLis not longer than the length (XHIS+W/2), the control device 10maintains the state in which the left-side region is set as the settableregion for the recommended available parking space Mr.

As illustrated in FIG. 4E, after the settable region for the recommendedavailable parking space Mr is set to the left side, when the left-sidelateral distance XL is not longer than the length (XHIS+W/2), thecontrol device 10 maintains the state in which the settable region forthe recommended available parking space Mr is set at the left side. Onthe other hand, as illustrated in FIG. 4F, after the settable region forthe recommended available parking space Mr is set to the left side, whenthe subject vehicle travels on the right side of the center line and theleft-side lateral distance XL is longer than the length (XHIS+W/2), thecontrol device 10 changes the settable region for the recommendedavailable parking space Mr from the left-side region to the right-sideregion. Through this operation, selection between the right side and theleft side when set as the settable region can have a hysteresischaracteristic with respect to the lateral position of the subjectvehicle. For example, when the left-side region is set as the settableregion for the recommended available parking space Mr, the recommendedavailable parking space Mr is preferentially displayed on the left-sideregion as compared with the right side. This makes it possible tosuppress the occurrence of hunting of the recommended available parkingspace Mr on the display screen of the display 21. In the abovedescription, the left-side region is set as the settable region for therecommended available parking space Mr and the settable region for therecommended available parking space Mr is changed in accordance with thecomparison result between the lateral distance (XL) of the subjectvehicle and the length (XHIS+W/2), but when the right-side region is setas the settable region for the recommended available parking space Mr,the settable region for the recommended available parking space Mr maybe changed in accordance with the comparison result between the lateraldistance (XR) of the subject vehicle and the length (XHIS+W/2).

When the number of the available parking spaces Me is less than thepredetermined value, the control device 10 sets the display mode to anormal mode. In the normal mode, no settable region is set. When theparking area includes few empty parking spaces, prompt presentation ofthe empty parking spaces to the driver and passengers may be moreimportant than preventing the hunting. Thus, the convenience of thesystem for the driver and passengers can be improved.

When the subject vehicle stops from the state of moving as illustratedin FIGS. 7A and 7B, the display screen of the display 21 becomes ascreen as illustrated in FIG. 7C. FIG. 7C is a third view for describingan example of a display screen in the parking assist process accordingto the present embodiment. The display screen of FIG. 7C is a displayscreen when the vehicle stops at the position P3 in FIG. 4C.

As illustrated in the display screen of FIG. 7C, the user finds themessages included in the image 21C and can confirm that selection andinput of the target parking space Mo are required. The user designatesthe available parking space PL5, which is presented as the recommendedavailable parking space Mr, as the target parking space Mo. The usertouches the available parking space PL5, which is displayed on the touchpanel-type display 21, thereby to designate this available parking spaceas the target parking space Mo. The display screen of the display ischanged from the display screen of FIG. 7C to the display screen of FIG.7D.

FIG. 7D is a fourth view for describing an example of a display screenin the parking assist process according to the present embodiment. Thedisplay screen of FIG. 7D is a display screen when the vehicle stops atthe position P4 in FIG. 4D.

The control device 10 controls the display 21 to display the displayscreen as illustrated in FIG. 7D thereby to present the target parkingspace Mo to the driver and passengers. The driver and passengers findthe messages included in the image 21C and can confirm that theautomated driving can be started.

FIG. 7E is a fifth view for describing an example of a display screen inthe parking assist process according to the present embodiment. When theautomated driving is started, the display screen of the display 21becomes a screen as illustrated in FIG. 7E, and the subject vehiclemoves forward. At this time, the image 21C is displayed with messagesinforming that the subject vehicle is moving forward by the automateddriving and that the driver and passengers should gaze around thesubject vehicle.

In the present embodiment, a determination may be made as to whether ornot the subject vehicle decelerates, and when the recommended availableparking space is displayed in a state in which the subject vehicledecelerates, the recommended available parking space may be prohibitedfrom changing to another available parking space. In general, the casein which a vehicle decelerates in the vicinity of the parking space mayoften be a case in which the driver or passenger determines therecommended available parking space as the target parking space andstarts parking. If, at that time, the recommended available parkingspace changes, it will be difficult for the driver or passenger toselect the recommended available parking space into which the driver orpassenger intends to park. Thus, the recommended available parking spaceis prohibited from changing to another available parking space, and therecommended available parking space into which the driver or passengerintends to park can thereby be maintained and displayed.

As described above, according to the present embodiment, availableparking spaces are detected, a recommended available parking space isset among the detected available parking spaces in accordance with thetraveling state of the subject vehicle, and the set recommendedavailable parking space is displayed on the display 21. Through thisoperation, an available parking space suitable for the automated drivingcan be presented to the driver and passengers.

According to the present embodiment, the required time for parking whenthe subject vehicle is parked into each of the available parking spacesis calculated, and among the available parking spaces, an availableparking space with which the required time for parking is shorter than apredetermined time is set as the recommended available parking space.Through this operation, an available parking space with which therequired time for parking is short can be presented to the driver andpassengers.

According to the present embodiment, the required time for parking whenthe subject vehicle is parked into each of the available parking spacesis calculated, and among the available parking spaces, an availableparking space with which the required time for parking is shortest isset as the recommended available parking space. Through this operation,the available parking space with which the required time for parking isshortest can be presented to the driver and passengers.

According to the present embodiment, a position separate from thesubject vehicle by a given gaze point distance is specified as a gazepoint, and among the available parking spaces, an available parkingspace with which the distance from the gaze point to the availableparking space is shorter than a predetermined distance threshold is setas the recommended available parking space. Through this operation, anavailable parking space suitable for the automated driving can bepresented to the driver and passengers while reflecting the intention ofthe user.

According to the present embodiment, a position separate from thesubject vehicle by a given gaze point distance is specified as a gazepoint, and among the available parking spaces, an available parkingspace with which the distance from the gaze point to the availableparking space is shortest is set as the recommended available parkingspace. Through this operation, an available parking space suitable forthe automated driving can be presented to the driver and passengerswhile reflecting the intention of the user.

According to the present embodiment, the ease of entry when the subjectvehicle is parked into each of the available parking spaces by theautomated driving is evaluated, and among the available parking spaces,an available parking space into which entry is easiest is set as therecommended available parking space. Through this operation theavailable parking space into which the entry is easiest can be presentedto the driver and passengers.

According to the present embodiment, among a first available parkingspace and a second available parking space that are disposed side byside along a direction parallel to the travel direction of the subjectvehicle, the first available parking space farther from the subjectvehicle than the second available parking space is set as therecommended available parking space. In a state in which the vehiclespeed of the subject vehicle decreases, the recommended availableparking space is prohibited from moving from the first available parkingspace to the second available parking space on the display screen of thedisplay 21. Through this operation, unnatural movement of therecommended available parking space Mr can be prevented.

According to the present embodiment, when the recommended availableparking space is displayed in a state in which the subject vehicledecelerates, the recommended available parking space is prohibited fromchanging to another available parking space. Through this operation, therecommended available parking space can be maintained and displayedwhile making aware of the driver's intention (passengers' intention) ofparking.

According to the present embodiment, when parking spaces are present atthe right and left with respect to the travel direction of the subjectvehicle, one of the right and left regions is set as a settable regionfor the recommended available parking space in accordance with thetraveling state of the subject vehicle, and a parking space included inthe settable region is set as the recommended available parking space.This can suppress a phenomenon that the frame of the recommendedavailable parking space is repeatedly displayed at the right and left onthe display screen of the display 21 (hunting).

According to the present embodiment, the distance from the parking spacelocated on a side of the subject vehicle to the subject vehicle iscalculated as a lateral distance, and one of the right and left regionsis set as the settable region for the recommended available parkingspace in accordance with the length of the lateral distance. Thecharacteristic when one of the right and left regions is selected is ahysteresis characteristic with respect to the length of the lateraldistance. This can suppress a phenomenon that the frame of therecommended available parking space is repeatedly displayed at the rightand left on the display screen of the display 21 (hunting).

According to the present embodiment, when a predetermined number or moreof the available parking spaces are present, an available parking spacelocated at one of the right and left is set as the recommended availableparking space in accordance with the traveling situation of the subjectvehicle. This can suppress a phenomenon that the frame of therecommended available parking space is repeatedly displayed at the rightand left on the display screen of the display 21 (hunting).

In the present embodiment, the number of recommended available parkingspaces set by the control device 10 is not limited to one and may be twoor more. The number of recommended available parking spaces displayed onthe display 21 is also not limited to one and may be two or more.

In the present embodiment, to prevent the display screen of the display21 from showing an unnatural movement such that the frame of therecommended available parking space Mr returns below on the screen, ahysteresis characteristic is given to the relationship between thevehicle speed and the gaze point distance, but the control may bemodified as below. As illustrated in FIG. 4C, the control device 10 setsthe available parking space PL5 as the recommended available parkingspace and controls the display 21 to display the recommended availableparking space. As the subject vehicle decelerates, the control device 10sets the available parking space PL4 as the recommended availableparking space. The control device 10 controls the display 21 to continueto display the available parking space PL5 as the recommended availableparking space rather than displaying the set available parking spacePL4. That is, in the setting control for the recommended availableparking space, even when the position of an available parking spacerelatively moves in the direction of approaching the subject vehicle dueto decrease of the vehicle speed, the display position of therecommended available parking space is fixed on the display screen ofthe display 21. This can prevent the unnatural movement of therecommended available parking space Mr.

In the present embodiment, the available parking space Me closest to thegaze point is set as the recommended available parking space Mr, but theavailable parking space Me with which the distance from the gaze pointto the available parking space Me is shorter than a predetermineddistance threshold may be set as the recommended available parking spaceMr. When there is a plurality of recommended available parking spaces Mrthat can be set in accordance with the distances from the gaze point tothe available parking spaces Me, an available parking space with whichthe parking-related cost is low may be set as the recommended availableparking space Mr.

Second Embodiment

The parking assist system according to another embodiment of the presentinvention will be described. This embodiment is different from theabove-described first embodiment in that the length of the gaze pointdistance is changed in accordance with the travel direction of thesubject vehicle. Other configuration is the same as that of the firstembodiment, and the description is borrowed herein.

FIGS. 8A-8B are a set of views for describing an example of the parkingassist process according to the present embodiment. FIG. 8A illustratesa view when the subject vehicle is parked into the target parking spaceMo from a state in which the subject vehicle is traveling forward(forward state). FIG. 8B illustrates a view when the subject vehicle isparked into the target parking space Mo from a state in which thesubject vehicle is traveling backward (backward state).

In FIG. 8A, it is assumed that the current position of the subjectvehicle is P6, the gaze point when the position of the subject vehicleis P6 is G6, and the turning point is P7. In FIG. 8B, it is assumed thatthe gaze point when the position of the subject vehicle is P6 is Gb. Thegaze point Ga is a gaze point when set from the same gaze point distanceas that in the forward state.

In a state in which the subject vehicle is traveling forward asillustrated in FIG. 8A, when the subject vehicle is parked into theavailable parking space PL5 in the backward parking (a parking state inwhich the subject vehicle can move forward to exit from the availableparking space), the subject vehicle stops in the vicinity of the gazepoint, then moves forward to the turning point P7, turns for parking atthe point P7, moves backward to the available parking space PL5, andparks into the available parking space PL5. On the other hand, in astate in which the subject vehicle is traveling backward as illustratedin FIG. 8B, when the subject vehicle is parked into the availableparking space PL5 in the backward parking, the subject vehicle stops atthe start position of the automated driving and then moves backward fromthe start position of the automated driving to the available parkingspace PL5 to park into the available parking space PL5 without turningfor parking.

When the subject vehicle is traveling forward, the distance between thestart position of the automated driving and the target parking space Mois short. On the other hand, when the subject vehicle is travelingbackward, the distance between the start position of the automateddriving and the target parking space Mo is longer than that when thesubject vehicle is traveling forward because the subject vehicle doesnot turn for parking.

FIG. 9 is a graph illustrating a relationship between the vehicle speed(V [km]) and the gaze point distance (Y [m]). The solid line indicates acharacteristic in the backward state while the dotted line indicates acharacteristic in the forward state. In the forward state, when thevehicle speed is lower than Vc, the gaze point distance is Ya. When thevehicle speed is within a range of Vc or higher and lower than Vd, thegaze point distance increases in proportion to the vehicle speed. Whenthe vehicle speed is not lower than Vd, the gaze point distance is Yb.In the backward state, when the vehicle speed is lower than Ve(Vc<Ve<Vd), the gaze point distance is Yc (Ya<Yc<Yb). When the vehiclespeed is within a range of Ve or higher and lower than Vd, the gazepoint distance increases in proportion to the vehicle speed. When thevehicle speed is not lower than Vd, the gaze point distance is Yb. Thegaze point distance Yc is preliminarily set in accordance with thelength of the travel route when the automated operation is performedfrom the state in which the vehicle moves backward.

As illustrated in FIG. 9, when the vehicle speed becomes lower than Vein a state in which the subject vehicle is traveling backward, the gazepoint distance is set to Yc which is longer than the gaze point distance(Ya) in the forward state. The gaze point (corresponding to the startposition of the automated driving) located behind the subject vehicle istherefore set to be far. The recommended available parking space set inthe vicinity of the gaze point is set at a position separate from thesubject vehicle accordingly. That is, in the present embodiment, anappropriate length of the gaze point distance can be set to match eachof the travel route when parking by the automated driving from theforward state and the travel route when parking by the automated drivingfrom the backward state.

As described above, according to the present embodiment, the length ofthe gaze point distance is set in accordance with whether the traveldirection of the subject vehicle is forward or backward. Through thisoperation, a parking space suitable for the automated driving can bepresented to the driver and passenger in accordance with the traveldirection of the subject vehicle in the parking area.

REFERENCE SIGNS LIST

-   1000 Parking assist system-   100 Parking assist apparatus-   10 Control device-   11 CPU-   12 ROM-   13 RAM-   20 Output device-   21 Display-   22 Speaker-   23 Lamp-   1 a-1 d On-board cameras-   2 Image processing device-   3 Ranging device-   30 Vehicle controller-   40 Drive system-   50 Steering angle sensor-   60 Vehicle speed sensor-   V Vehicle-   Me Available parking space-   Mr Recommended available parking space-   Mo Target parking space

The invention claimed is:
 1. A parking assist method for assistingparking of a subject vehicle using a parking assist apparatus comprisinga controller that guides the subject vehicle to a parking space and adisplay that displays parking spaces, the parking assist methodcomprising: specifying, with the controller, available parking spacesinto which the subject vehicle can be parked; detecting, using one orboth of a sensor and camera, an available parking space suitable forparking of the subject vehicle from among the specified availableparking spaces in accordance with a traveling state of the subjectvehicle; setting, with the controller, the detected available parkingspace as a recommended available parking space; and when the recommendedavailable parking space is displayed by the display in a state in whichthe subject vehicle decelerates during detection of the recommendedavailable parking space, prohibiting, with the controller, therecommended available parking space from changing to another availableparking space.
 2. A parking assist method for assisting parking of asubject vehicle using a parking assist apparatus comprising a controllerthat guides the subject vehicle to a parking space and a display thatdisplays parking spaces, the parking assist method comprising:specifying, with the controller, available parking spaces into which thesubject vehicle can be parked; when parking spaces are present at rightand left with respect to a travel direction of the subject vehicle,setting, with the controller, one of right and left regions to asettable region for the recommended available parking space inaccordance with a traveling state of the subject vehicle; setting, withthe controller, the parking space included in the settable region to arecommended available parking space; and displaying the recommendedavailable parking space on the display.
 3. The parking assist methodaccording to claim 2, further comprising calculating a lateral distancethat is a distance from the parking space located on a side of thesubject vehicle to the subject vehicle, wherein one of the right andleft regions is set as the settable region for the recommended availableparking space in accordance with a length of the lateral distance, and acharacteristic when one of the right and left regions is selected is ahysteresis characteristic with respect to the length of the lateraldistance.
 4. The parking assist method according to claim 2, furthercomprising estimating an intention of a driver or passenger of thesubject vehicle in accordance with a traveling state of the subjectvehicle; wherein the recommended available parking space is set amongthe specified available parking spaces in accordance with the intentionof the driver or passenger.
 5. The parking assist method according toclaim 4 wherein the intention of the driver or passenger is estimated onan assumption that the traveling state is represented by at least one ofa traveling position of the subject vehicle and a vehicle speed of thesubject vehicle.
 6. The parking assist method according to claim 2,further comprising: setting the recommended available parking spacedisplayed on the display to the target parking space for the subjectvehicle on a basis of an operation by a driver or passenger of thesubject vehicle; and performing automated control of the subject vehicleto park the subject vehicle into a target parking space.
 7. The parkingassist method according to claim 2, further comprising calculating arequired time each of the available parking spaces, the required timebeing a time required for parking when the subject vehicle is parked,wherein the available parking space with which the required time forparking is shorter than a predetermined time is set as the recommendedavailable parking space.
 8. The parking assist method according to claim2, further comprising calculating a required time each of the availableparking spaces, the required time being a time required for parking whenthe subject vehicle is parked, wherein the available parking space withwhich the required time for parking is shortest is set as therecommended available parking space.
 9. The parking assist methodaccording to claim 2, further comprising specifying a gaze point whichis separated from the subject vehicle by a given gaze point distance,wherein the available parking space with which a distance from the gazepoint to the available parking space is shorter than a predetermineddistance threshold is set as the recommended available parking space.10. The parking assist method according to claim 9, wherein a length ofthe gaze point distance is set in accordance with whether a traveldirection of the subject vehicle is forward or backward.
 11. The parkingassist method according to claim 2, further comprising specifying a gazepoint which is separated from the subject vehicle by a given gaze pointdistance, wherein the available parking space with which a distance fromthe gaze point to the available parking space is shortest is set as therecommended available parking space.
 12. The parking assist methodaccording to claim 2, further comprising evaluating ease of entry whenthe subject vehicle is parked into each of the available parking spaces,wherein the available parking space into which entry is easiest is setas the recommended available parking space.
 13. A parking assist methodfor assisting parking of a subject vehicle using a parking assistapparatus comprising a controller that guides the subject vehicle to aparking space and a display that displays parking spaces, the parkingassist method comprising: specifying, with the controller, availableparking spaces into which the subject vehicle can be parked; setting,with the controller, the available parking space located at one of rightand left to the recommended available parking space in accordance with atraveling situation of the subject vehicle when a predetermined numberor more of the available parking spaces are present and; displaying therecommended available parking space on the display.
 14. A parking assistapparatus comprising: a display configured to display parking spaces;and a controller configured to guide the subject vehicle to a parkingspace, wherein the controller is configured to: specify availableparking spaces into which the subject vehicle can be parked; detect,using one or both of a sensor and a camera, an available parking spacesuitable for parking of the subject vehicle from among the specifiedavailable parking spaces in accordance with a traveling state of thesubject vehicle; set the detected available parking space as arecommended available parking space; control the display to display therecommended available parking space; when the recommended availableparking space is displayed in a state in which the subject vehicledecelerates during detection of the recommended available parking space,prohibit the recommended available parking space from changing toanother available parking space; set the recommended available parkingspace displayed on the display as a target parking space for the subjectvehicle on a basis of an operation by a driver or passenger of thesubject vehicle; and perform automated control of the subject vehicle topark the subject vehicle into the target parking space.